Steel plating method



Patented Aug. 21, 1951 STEEL PLATING METHOD Arthur Arent, Fort Dodge, Iowa No Drawing. ApplicationJanuarylO, 1946,

Serial No. 640,388

,4 Claims. (ill- 117 130) This invention relates to the art of bonding metallic surfaces or coatings to metal objects such as. steel or iron, and more particularly relates to a cold-plating method of bonding metallic antimony on steel or iron.

In. many instances, it is desirable to surfacecoat steel and iron objects to render their exposed surfaces corrosion resistant. Antimony has been known to be highly satisfactory for this purpose, but in the past, the only satisfactory carriers for the antimony have been volatile, inflammable compositions, which present a fire and health hazard.

It is an object of the present invention to provide a simple, economical and efficient process for causing a deposition of metallic antimony in commingled union with exposed steel and iron surfaces.

Another object of this invention is to. provide a cold-plating process for applying antimony plating to steel or iron, in which the plate forms an integral body with the steel and iron and contains few, if any, surface pinhole openings.

Still another object of this invention is to produce antimony-plated iron or steel having a high degree of corrosion resistance and which plating metal maybe combined with a silicate composition to produce an integral coating having a glossy appearance.

Still another object of this invention is to provide an antimony-plating process by which a succession of integrally bonded plates can be formed in commingled union with the surface of steel or iron objects.

Other objects reside in the provision of novel steps and treatments, all of which will be fully explained in the course of the following description.

The present invention resides in the discovery that when an antimony-carrying brine is applied to clean iron or steel surfaces a reaction results which forms a commingled union of antimony with the iron or steel. The surface deposit, so formed, is a continuous layer or film, which is substantially, if not entirely, free from pinhole openings, and is formed integrally with the base metal. Likewise, if desired the clean metallic surface may be initially coated with water glass, after which the antimony-carrying solution is applied to the silicate surface and reacts with it and the underneath metal to form a glossy integral surface coating.

With this understanding of the general nature of the present invention, typical operations will be cited to provide a better understanding of the practice of the invention. In the. first of.

these a piece of steel was suitably cleaned as by sand blasting. and the coating composition applied to the cleaned surface by brushing.

This composition was formed by introducingv one pound of common salt'(NaCl) into one pint of rain water. This mixture was stirred to dissolve the salt and the excess salt was allowed. to remain. One-half pound antimony trich l oride (crystals) was added to the brine and stirred. until the antimony was dissolved. This( matingv wasallowedto dry thoroughly before While I prefer to employ sodium chloride in;

preparing the brine of the treatment,it is pos' sible to obtain satisfactory results by using other chlorides, such as potassium chloride or calcium.

chloride, in forming the brine.

In another test operation a piece of clean steel: was initially coated with a solution of commercial. If desired, thesodium silicate solution may be thinned with distilled or rain Water before coating the metal as. aforesaid. After drying this base coating, the antimony-carrying brine is applied thereto as by brushing, or immersion, and when this second. coating has dried, it is rinsed to complete the:

water glass (sodium silicate).

treatment.

As in the previous example, a plurality of coat--- ings may be applied to the base coating by omitting the rinsing step until the final coating: has been applied. The coating is relatively thick and there is no apparent division between the antimony layer and the base metal, although intermediate these there is a layer which apparently is a mixture of both metals. The glasslike deposit which is intermingled with the metallic antimony is substantially or entirely free from pinhole openings and is water insoluble, and. hence makes an excellent preservative for the base metal surface which otherwise would be exposed.

In the formation of all the aforesaid coatings, a film or residue, which apparently is oxide, in

intermediate that it has all the appearance and. characteristics of oxide, forms at the surface when the coatin is dry and has adhesive properties which are particularly suited for the reception of other coatings or finishes, such as paints or lacquers when such finishes are desired.

Consequently, in industrial application, railway car bodies, automobile bodies, fuel storage tanks and many similar objects may be treated to render the metal resistant to the deteriorating effects of salt or other corrosive atmospheres and then painted or lacquered to produce the desired ornamental effects.

In the foregoing description, I have referred to the use of rain water or distilled water as best results will be obtained when the aqueous medium is free from salts, such as those carried in many domestic water systems. However, it should be understood that any brine, when its salt content is at or near the saturation point, will be satisfactory for most purposes. Likewise, I prefer to use anhydrous antimony trichloride in preparing the treatment solution, but antimony chloride or, in fact, metallic antimony obtained from any source and dissolved in the brine solution will give workable results. Best results are obtained when the anhydrous antimony trichloride is introduced in the amount of four pounds per gallon of brine used, but workable results can be obtained by using lesser amounts.

While I have used the term cold-plating process in the specification to indicate the absence of heat or electric current in the treatment, as normal room temperatures are satisfactory, I do not intend such definition to exclude the use of hot solutions when they are needed for any other reason. In the various drying steps aforementioned, natural drying may be used, but if it is desired to accelerate the action, heating or other types of artificial drying may be used.

If the plating operation utilizes an immersion treatment, best results will be obtained if the material under treatment is submerged for an interval of at least three minutes. If a brushing action is used, every part of the surface should be wet brushed several times before permitting it to dry.

What is claimed is:

1. The process for treating ferrous metal surfaces which comprises applying water glass to the surface to be coated, wetting the water glass surface after drying with a strong chloride solution carrying antimony dissolved therein for an interval sufficient to induce a surface reaction between antimony, the ferrous metal and water glass constituents, and drying the surface so reacted after metallic antimony has deposited on said surfaces.

2. The process for treating ferrous metal surfaces which comprises applying an alkali metal silicate solution to the surface to be coated, wetting'the coated surface after drying with a strong solution having antimony ions and an excess of chloride ions therein for an interval sufficient to induce a surface reaction between antimony, the base metal and water glass constituents, and drying the surface so reacted after metallic antimony has deposited on said surfaces.

3. A process as. defined in claim 2, in which the alkali metal silicate solution is formed by introducing sodium silicate in rain water.

4. A process as defined in claim 2, in which the alkali metal silicate solution is formed by introducing sodium silicate in distilled water.

ARTHUR ARENT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,186,217 Mark June 6, 1916 1,207,218 Roux Dec. 5, 1916 1,436,729 Scanlon Nov. 28, 1922 1,770,828 Arent July 15, 1930 2,271,706 Morris Feb. 3, 1942 2,485,182 Arent Oct. 18, 1949 OTHER REFERENCES Mellor: Comprehensive Treatise on Inorganic and Theoretical Chemistry, 1929, vol. 9, page 474. 

2. THE PROCESS FOR TREATING FERROUS METAL SURFACES WHICH COMPRISES APPLYING AN ALKALI METAL SILICATE SOLUTION TO THE SURFACE TO BE COATED, WETTING THE COATED SURFACE AFTER DRYING WITH A STRONG SOLUTION HAVING ANTIMONY IONS AND AN EXCESS OF CHLORIDE IONS THEREIN FOR AN INTERVAL SUFFICIENT TO INDUCE A SURFACE REACTION BETWEEN ANTIMONY, THE BASE METAL AND WATER GLASS CONSTITUENTS, AND DRYING THE SURFACE SO REACTED AFTER METALLIC ANTIMONY HAS DEPOSITED ON SAID SURFACES. 